(1) Field of the Invention
The present invention relates to a process for the preparation of aromatic sulfone compounds. More particularly, the present invention relates to a process for preparing an aromatic sulfone compound, at high efficiency under mild conditions; by reacting an aromatic hydrocarbon with a halogenated sulfonic acid in the presence of a Lewis acid.
(2) Description of the Related Art
As known processes for the preparation of aromatic sulfone compounds, there can be mentioned a process in which an alkylbenzene and sulfuric acid are heated (Japanese Patent Publication No. 60-92256), a process in which an alkylbenzene-sulfonic acid and an alkylbenzene are heated in polyphosphoric acid [J. Org. Chem., 32, 2931 (1967)], and a process in which an alkylbenzenesulfonyl chloride is heated and reacted with an alkylbenzene at 140.degree. to 220.degree. C. in the presence of FeCl.sub.3 or polyphosphoric acid (Izv. Vyssh. Ucheeb. Zaved., Khim. Khim. Tekhnol., 1969, 1588 and India J. Chem., Sect. B 1977, 1088).
However, these processes are defective in that heating is conducted for a long time, the yield is low, a large quantity of an acid solvent is used and the reaction should be carried out in multiple stages. Accordingly, these processes are not completely satisfactory as a process for preparing a sulfone compound at a low cost on an industrial scale.
Aromatic sulfone compounds or sulfonyl compounds are industrially valuable as synthetic intermediates for medicines, dyes and the like, and as starting materials for the production of polysulfone type resins. Accordingly, development of a process for preparing an aromatic sulfone compound in a shorter time and a higher yield by simpler steps with use of a smaller amount of an acid solvent is eagerly desired in the art.